JP-2011-38465A shows an internal combustion engine having a main combustion chamber and an auxiliary chamber. A spring member is disposed in the auxiliary chamber to generate a swirl flow. An air flowing into the auxiliary chamber from the main combustion chamber and a fuel supplied to the auxiliary chamber are homogeneously mixed, whereby an ignitability of the fuel in the auxiliary chamber can be stabilized.
However, it is still necessary to improve a spread of a flame jet which is injected from the auxiliary chamber to the main combustion chamber.